Phosphor, ceramic plate, and light-emitting module

Abstract

To provide a novel phosphor.SOLUTION: The general formula of the phosphor is represented by MaY3-a-bAl5-a+cSia-2cPcO12:Ceb, where M represents at least one element selected from a group consisting of Ba, Sr, Ca and Mg; a and b are values included in a range surrounded by a straight line represented by b=0.1135a+0.0754, a straight line represented by b=0.0816a+0.02, a straight line represented by a=0.01, and a straight line represented by b=0.12; and c is a value satisfying 0≤c<a / 2.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a phosphor.

Background Art

[0002] Conventionally, a white light source combining a YAG phosphor and a blue LED has been widely known. On the other hand, with the increase in the brightness of the light source, temperature quenching has occurred due to heat concentration caused by wavelength conversion (Stokes loss) in the YAG phosphor, leading to a decrease in the efficiency of the white light source. Therefore, Ba and Si were dissolved in the YAG phosphor to obtain BaY 1.92 Al4SiO 12 :Ce 0.08 has been devised (see Non-Patent Document 1). This phosphor has better temperature characteristics than the conventional YAG phosphor (Y3Al5O 12 :Ce), and the emission intensity retention rate when the temperature is raised from 25°C to 200°C is 91.5%, and it is difficult to cause temperature quenching.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the aforementioned BaY 1.92 Al4SiO 12 :Ce 0.08There are limitations to the chromaticity range achievable with the yellow phosphor represented by .

[0005] The present invention has been made in view of such circumstances, and one of its objectives is to provide a novel phosphor.

Means for Solving the Problems

[0006] To solve the above problems, a phosphor according to an aspect of the present invention has a general formula M a Y 3-a-b Al 5-a+c Si a-2c P c O 12 :Ce b (However, M represents at least one element selected from the group consisting of Ba, Sr, Ca, and Mg. a and b are values included in the range surrounded by the straight line represented by b = 0.1135a + 0.0754, the straight line represented by b = 0.0816a + 0.02, the straight line represented by a = 0.01, and the straight line represented by b = 0.12. c is a value of 0 ≦ c < a / 2.)

[0007] According to this aspect, a novel phosphor with good emission characteristics and temperature characteristics can be realized.

[0008] The crystal structure may be a garnet type.

[0009] It may be excited by blue light having a peak wavelength in the range of 430 to 480 nm and emit yellow light having a dominant wavelength in the range of 567 to 572 nm. Thereby, a novel yellow phosphor can be realized.

[0010] The volume average particle diameter may be 1 to 30 μm.

[0011] a and c may satisfy the equations a / c - 2 < 8.0 and 0.01 ≦ c ≦ 0.16. Thereby, the shift amount of the dominant wavelength when the phosphor is heated can be reduced.

[0012] Another aspect of the present invention is a light-emitting module. This light-emitting module includes an LED that emits blue light with a peak wavelength in the range of 430 to 480 nm, and a wavelength-converting layer that is excited by the blue light emitted by the LED and emits yellow light. The wavelength-converting layer contains the phosphor described above. The light-emitting module has a mixed color of blue light and yellow light such that the chromaticity coordinates (cx, cy) are within the range surrounded by (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309).

[0013] The wavelength-converting layer may contain 0.1 to 30 vol% of the phosphor in a resin that is transparent to visible light, and may have a thickness of 0.01 to 5 mm. Thereby, it is possible to achieve a desired luminous efficiency and realize a light-emitting module having a chromaticity within the above range.

[0014] The wavelength-converting layer may be a ceramic plate having a thickness of 0.01 to 2.0 mm. Thereby, it is possible to achieve a desired luminous efficiency and realize a light-emitting module having a chromaticity within the above range.

[0015] Any combination of the above components, as well as those obtained by converting the expression of the present invention among manufacturing methods, devices such as lamps and lighting, light-emitting modules, light sources, etc., are also effective as aspects of the present invention.

Advantages of the Invention

[0016] According to the present invention, a novel phosphor can be provided.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. Further, the embodiments are illustrative and not restrictive of the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0019] (First Embodiment) [Phosphor] The phosphor according to this embodiment is a phosphor that is efficiently excited by blue light and emits light. Specifically, it shows strong excitation by blue light with a peak wavelength in the range of 430 to 480 nm, and emits yellow light with a dominant wavelength in the range of 567 to 572 nm. Further, the phosphor according to this embodiment has a garnet-type crystal structure, and realizes yellow light emission by doping an activator such as Ce 3+ ions.

[0020] Next, the phosphor according to this embodiment will be described in detail. The phosphor according to this embodiment has a general formula of Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b (However, a and b are values included in the range surrounded by the straight line represented by b = 0.1135a + 0.0754, the straight line represented by b = 0.0816a + 0.02, the straight line represented by a = 0.01, and the straight line represented by b = 0.12).

[0021] Figure 1 is a chromaticity diagram (CIE1931) showing the chromaticity of the emission colors of a conventional yellow phosphor and a blue LED. The point C1 shown in Figure 1 is the chromaticity coordinates of a known phosphor (BaY 1.92 Al4SiO 12 :Ce 0.08 ) obtained by solid-solubilizing Ba and Si in a YAG phosphor, and the dominant wavelength of this known phosphor is 566.3 nm. On the other hand, the point C2 is the chromaticity coordinates of an example of a blue LED with a peak wavelength in the range of 430 to 480 nm.

[0022] Also, the range R1 is a chromaticity range defined as white light for a specific application (vehicle headlight). Specifically, the range R1 is the range surrounded by the chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), (0.311, 0.309).

[0023] The mixed light combining yellow light from a known phosphor and blue light from an LED has a chromaticity on the straight line connecting point C1 and point C2. Therefore, as shown in FIG. 1, when the dominant wavelength of the yellow light is on the long wavelength side, white light included in the range R1 cannot be realized unless the blue LED is changed. Thus, a phosphor whose dominant wavelength is shifted to the long wavelength side compared to a conventional yellow phosphor, such as the yellow phosphor of the present invention, is required.

[0024] FIG. 2 is a diagram for explaining the range of the dominant wavelength targeted by the yellow phosphor according to the present embodiment. The yellow phosphor according to the present embodiment requires that the straight line connecting the chromaticity (cx2, cy2) of the blue LED and the chromaticity (cx1, cy1) of the yellow phosphor passes through the range R1 in order to realize the chromaticity range defined as white light for a vehicle headlight in combination with the blue LED.

[0025] According to the study by the inventors of the present application, the dominant wavelength when the straight line connecting the chromaticity (cx2, cy2) of the blue LED at point C2 and the chromaticity (cx1', cy1') of the yellow phosphor at point C1' touches at the upper part of the chromaticity range R1 is 567.4 nm. Similarly, the dominant wavelength when the straight line connecting the chromaticity (cx2, cy2) of the blue LED at point C2 and the chromaticity (cx1", cy1") of the yellow phosphor at point C1" touches at the lower part of the chromaticity range R1 is 570.6 nm.

[0026] Therefore, the yellow phosphor according to the present embodiment preferably has a dominant wavelength in the range of 567 to 572 nm, and more preferably in the range of 567.4 to 570.6 nm.

[0027] Hereinafter, it will be described more specifically using comparative examples and examples. However, the descriptions of the raw materials, manufacturing methods, chemical compositions of the phosphors, etc. below do not limit the embodiments of the phosphors of the present invention in any way.

[0028] (Comparative Example 1) The phosphor according to Comparative Example 1 is Ba 1.00 Y 1.92 Al4.00 Si 1.00 :Ce 3+ 0.08 It is a phosphor represented by. The phosphor according to Comparative Example 1 is manufactured by the following method. First, powder raw materials of BaCO3 (99.9%: manufactured by Kanto Chemical Co., Inc.), Y2O3 (99.9%: manufactured by High Purity Chemical Laboratory Co., Ltd.), CeO2 (99.99%: manufactured by High Purity Chemical Laboratory Co., Ltd.), α-Al2O3 (99.99%: manufactured by High Purity Chemical Laboratory Co., Ltd.), and SiO2 (99.9%: manufactured by Tokuyama Corporation) are prepared. Then, each powder raw material is weighed so as to have a molar ratio of Ba = 1.00, Y = 1.92, Al = 4.00, Si = 1.00, and Ce = 0.08.

[0029] As a flux, BaF2 (99%: manufactured by High Purity Chemical Laboratory Co., Ltd.) is weighed at 5 wt% of the total weight of the powder raw materials, combined with the powder raw materials, and uniformly mixed in a mortar. Then, it is put into an alumina crucible (SSA-S B1: manufactured by Nikkato Corporation) and heated and sintered at 1550 °C for 4 h in a reducing atmosphere (H2:N2 = 5 / 95 (volume ratio)). After cooling to room temperature, it is pulverized in a mortar, and the luminescence characteristics of the phosphor excited by light with a wavelength of 460 nm are measured with a spectrophotometer (FP-8500: manufactured by JASCO Corporation).

[0030] As a result, the dominant wavelength λd of the phosphor according to Comparative Example 1 was 566.3 nm, and when the luminescence intensity maintenance rate (K) was evaluated when the temperature was raised from 25 °C to 200 °C, it was 91.5%. That is, the luminescence intensity when the temperature was raised to 200 °C decreased to 91.5% with respect to the luminescence intensity at 25 °C. Also, the internal quantum efficiency (IQE) was 95%, and the absorption rate (Abs) of the blue light emitted by the LED absorbed by the yellow-emitting phosphor was 80%, and results equivalent to those of known phosphors were obtained.

[0031] The results of the luminescence characteristics, temperature characteristics, etc. of the phosphors according to each example and each comparative example are summarized in Table 1. Note that Table 1 is described in order from Comparative Example 2 with the smallest charged amount of Ba. Also, in Table 1, when the dominant wavelength λd satisfies 567.4 nm ≤ λd ≤ 570.6 nm, it is indicated by ○, and when it does not satisfy, it is indicated by ×. Also, when the emission intensity maintenance rate (K) is 90% or more, it is indicated by ○, and when it is less than 90%, it is indicated by ×. Also, when the internal quantum efficiency (IQE) is 90% or more, it is indicated by ○, and when it is less than 90%, it is indicated by ×. Also, when the absorption rate (Abs) is 80% or more, it is indicated by ○, and when it is less than 80%, it is indicated by ×.

[0032]

Table 1

[0033] (Example 1) The phosphor according to Example 1 is Ba 0.05 Y 2.89 Al 4.95 Si 0.05 :Ce 3+ 0.06 The phosphor represented by. Except that the respective raw material powders similar to Comparative Example 1 were weighed so as to have a molar ratio of Ba = 0.05, Y = 2.89, Al = 4.95, Si = 0.05, Ce = 0.06, a phosphor was produced under the same conditions as Comparative Example 1, and the luminescence characteristics and temperature characteristics were evaluated.

[0034] As a result, the dominant wavelength of the phosphor according to Example 1 is 569.0 nm, which is included in the target wavelength range. Also, the internal quantum efficiency is 97%, the absorption rate is 84%, and the emission intensity maintenance rate is 93.0%. It can be seen that the performance exceeds the target value in all items and is improved compared to the phosphor according to Comparative Example 1. The results are shown in Table 1.

[0035] In addition, equivalent luminescence characteristics were obtained even in phosphors synthesized using raw materials prepared by mixing the raw materials of the phosphor by a liquid phase mixing method such as a citric acid sol-gel method, a hexamine method, or a urea method. Although various methods can be adopted for the method for manufacturing the phosphor according to the present embodiment, for example, when the solid phase method is used, impurities are less likely to enter by using high-purity powder raw materials, and the mixing of the raw materials can be completed in a short time (about 10 minutes). Further, when the liquid phase method is used, since mixing at the atomic level is possible, phosphors having a composition difference at the 1 / 100 mol level can be separately produced.

[0036] (Example 2) The phosphor according to Example 2 is a phosphor represented by Ba 0.05 Y 2.91 Al 4.95 Si 0.05 :Ce 3+ 0.04 A phosphor was produced under the same conditions as in Comparative Example 1 except that the respective raw material powders similar to those in Comparative Example 1 were weighed so as to have a molar ratio of Ba = 0.05, Y = 2.91, Al = 4.95, Si = 0.05, and Ce = 0.04, and the luminescence characteristics and temperature characteristics were evaluated.

[0037] As a result, the dominant wavelength of the phosphor according to Example 2 is 567.8 nm, which is included in the target wavelength range. Further, the internal quantum efficiency is 98%, the absorption rate is 82%, and the emission intensity maintenance rate is 95.0%. It can be seen that the performance exceeds the target value in all items and is improved compared to the phosphor according to Comparative Example 1. The results are shown in Table 1.

[0038] (Example 3) The phosphor according to Example 3 is a phosphor represented by Ba 0.05 Y 2.87 Al 4.95 Si 0.05 :Ce 3+ 0.08 A phosphor was produced under the same conditions as in Comparative Example 1 except that the respective raw material powders similar to those in Comparative Example 1 were weighed so as to have a molar ratio of Ba = 0.05, Y = 2.87, Al = 4.95, Si = 0.05, and Ce = 0.08, and the luminescence characteristics and temperature characteristics were evaluated.

[0039] As a result, the dominant wavelength of the phosphor according to Example 3 is 570.5 nm, which is within the target wavelength range. Also, the internal quantum efficiency is 97%, the absorption rate is 85%, and the emission intensity retention rate is 91.0%. It can be seen that all items exceed the target values, and the performance is improved compared to the phosphor according to Comparative Example 1. The results are shown in Table 1.

[0040] (Examples 4 - 6) The phosphors according to Examples 4 - 6 are phosphors represented by Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b where a = 0.10, b = 0.04 (Example 4), 0.06 (Example 5), 0.09 (Example 6). Except that each raw material powder similar to Comparative Example 1 was weighed to have a desired molar ratio, phosphors were prepared under the same conditions as Comparative Example 1, and the luminescence characteristics and temperature characteristics were evaluated.

[0041] As a result, for the phosphors according to Examples 4 - 6, characteristics within the target range were obtained in all items of dominant wavelength, internal quantum efficiency, absorption rate, and emission intensity retention rate. The results are shown in Table 1.

[0042] (Examples 7 - 9) The phosphors according to Examples 7 - 9 are phosphors represented by Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b where a = 0.03, b = 0.03 (Example 7), 0.04 (Example 8), 0.06 (Example 9). Except that each raw material powder similar to Comparative Example 1 was weighed to have a desired molar ratio, phosphors were prepared under the same conditions as Comparative Example 1, and the luminescence characteristics and temperature characteristics were evaluated.

[0043] As a result, for the phosphors according to Examples 7 - 9, characteristics within the target range were obtained in all items of dominant wavelength, internal quantum efficiency, absorption rate, and emission intensity retention rate. The results are shown in Table 1.

[0044] (Examples 10 to 12) The phosphors according to Examples 10 to 12 are Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b In the phosphor represented by a = 0.08, b = 0.03 (Example 10), 0.06 (Example 11), 0.08 (Example 12). Except that each raw material powder similar to Comparative Example 1 was weighed so as to have a desired molar ratio, phosphors were produced under the same conditions as in Comparative Example 1, and the luminescence characteristics and temperature characteristics were evaluated.

[0045] As a result, the phosphors according to Examples 10 to 12 obtained characteristics within the target ranges in all items of dominant wavelength, internal quantum efficiency, absorption rate, and emission intensity maintenance rate. The results are shown in Table 1.

[0046] (Examples 13 to 15) The phosphors according to Examples 13 to 15 are Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b In the phosphor represented by a = 0.20, b = 0.04 (Example 13), 0.08 (Example 14), 0.10 (Example 15). Except that each raw material powder similar to Comparative Example 1 was weighed so as to have a desired molar ratio, phosphors were produced under the same conditions as in Comparative Example 1, and the luminescence characteristics and temperature characteristics were evaluated.

[0047] As a result, the phosphors according to Examples 13 to 15 obtained characteristics within the target ranges in all items of dominant wavelength, internal quantum efficiency, absorption rate, and emission intensity maintenance rate (K). The results are shown in Table 1.

[0048] (Examples 16 to 18) The phosphors according to Examples 16 to 18 are Ba a Y 3-a-b Al 5-a Si a O 12:Ce b In the phosphor represented by b , a = 0.40, b = 0.06 (Example 16), 0.10 (Example 17), 0.12 (Example 18). Except that each raw material powder similar to Comparative Example 1 was weighed so as to have a desired molar ratio, phosphors were produced under the same conditions as in Comparative Example 1, and their luminescence characteristics and temperature characteristics were evaluated.

[0049] As a result, for the phosphors according to Examples 16 to 18, characteristics within the target ranges were obtained in all items of dominant wavelength, internal quantum efficiency, absorption rate, and luminescence intensity maintenance rate. The results are shown in Table 1.

[0050] (Comparative Example 2) The phosphor according to Comparative Example 2 is Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b In the phosphor represented by b , a = 0.01, b = 0.02. Except that each raw material powder similar to Comparative Example 1 was weighed so as to have a desired molar ratio, phosphors were produced under the same conditions as in Comparative Example 1, and their luminescence characteristics and temperature characteristics were evaluated.

[0051] As a result, for the phosphor according to Comparative Example 2, the internal quantum efficiency was 98% and characteristics within the target range were obtained, but characteristics within the target range were not obtained in the items of dominant wavelength, absorption rate, and luminescence intensity maintenance rate. The results are shown in Table 1.

[0052] (Comparative Example 3) The phosphor according to Comparative Example 3 is Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b In the phosphor represented by b , a = 0.01, b = 0.04. Except that each raw material powder similar to Comparative Example 1 was weighed so as to have a desired molar ratio, phosphors were produced under the same conditions as in Comparative Example 1, and their luminescence characteristics and temperature characteristics were evaluated.

[0053] As a result, for the phosphor according to Comparative Example 3, the dominant wavelength was 568.0 nm, the internal quantum efficiency (IQE) was 98%, and the absorption rate was 82%. Although the characteristics within the target ranges were obtained for these items, the emission intensity retention rate was 87%, and the characteristics within the target range were not obtained. The results are shown in Table 1.

[0054] (Comparative Example 4) In the phosphor represented by Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b a = 0.60 and b = 0.18. Phosphors were prepared under the same conditions as in Comparative Example 1 except that each raw material powder was weighed so as to have a desired molar ratio, and the emission characteristics and temperature characteristics were evaluated.

[0055] As a result, for the phosphor according to Comparative Example 4, the absorption rate was 86% and the characteristics within the target range were obtained. However, the characteristics within the target range were not obtained in terms of the dominant wavelength, internal quantum efficiency, and emission intensity retention rate. The results are shown in Table 1.

[0056] (Comparative Example 5) In the phosphor represented by Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b a = 0.70 and b = 0.13. Phosphors were prepared under the same conditions as in Comparative Example 1 except that each raw material powder was weighed so as to have a desired molar ratio, and the emission characteristics and temperature characteristics were evaluated.

[0057] As a result, for the phosphor according to Comparative Example 5, the dominant wavelength was 570.0 nm and the absorption rate was 86%. Although the characteristics within the target ranges were obtained for these items, the internal quantum efficiency was 87% and the emission intensity retention rate was 89%, and the characteristics within the target range were not obtained for these items. The results are shown in Table 1.

[0058] FIG. 3 is a diagram showing the relationship between the charged amounts of Ba and Ce and the dominant wavelength in the yellow phosphor according to the present embodiment. As shown in Table 1, the phosphors according to Examples 3, 6, 15, and 18 all have a dominant wavelength λd of 570.6 nm, which is the upper limit of the target range. When an approximate straight line is calculated based on the coordinates indicating the charged amounts (a, b) of Ba and Ce in each of these examples, the following equation L1 is obtained. Equation L1: b = 0.1135a + 0.0754

[0059] Similarly, the phosphors according to Examples 4, 7, 10, 13, and 16 all have a dominant wavelength λd of 567.4 nm, which is the lower limit of the target range. When an approximate straight line is calculated based on the coordinates indicating the charged amounts (a, b) of Ba and Ce in each of these examples, the following equation L1' is obtained. Equation L1': b = 0.0816a + 0.02

[0060] And if the charged amounts (a, b) of Ba and Ce are within the range sandwiched between the two straight lines L1 and L1', the dominant wavelength λd will be in the range of 567.4 nm ≤ λd ≤ 570.6 nm. On the other hand, the phosphors according to Comparative Examples 1, 2, and 4, whose charged amounts (a, b) of Ba and Ce are not within the range sandwiched between the two straight lines L1 and L1', do not have a dominant wavelength λd within the range of 567.4 nm ≤ λd ≤ 570.6 nm.

[0061] Also, in the range surrounded by the straight line of Equation L1 and the straight line of Equation L1', the charged amount of Ce tends to increase as the charged amount of Ba increases. The reason is that in the phosphor according to the present embodiment, as the amount of Ba increases, the emission intensity on the short-wavelength side near 530 nm tends to increase, and due to this effect, the dominant wavelength tends to shift to the short-wavelength side. To mitigate this tendency, the charged amount of Ce is increased to increase the emission on the long-wavelength side by multiple excitations. As a result, the charged amount of Ce increases as the charged amount of Ba increases.

[0062] Next, the charged amount (b) of Ce is examined. FIG. 4 is a diagram showing the relationship between the charged amount (b) of Ce and the internal quantum efficiency (IQE).

[0063] As shown in Fig. 4, the phosphor according to Example 18 with a Ce charge amount (b) of 0.12 mol has an internal quantum efficiency of 90%, and the characteristics within the target range are obtained. On the other hand, the phosphors according to Comparative Example 5 with a Ce charge amount (b) of 0.13 mol and Comparative Example 4 with a Ce charge amount (b) of 0.18 mol have an internal quantum efficiency of less than 90%, and the characteristics within the target range are not obtained. Therefore, the Ce charge amount (b) considering the internal quantum efficiency preferably satisfies the following formula L2. Formula L2: b ≦ 0.12

[0064] Also, as shown in Fig. 4, when the Ce charge amount (b) exceeds 0.09 mol, the internal quantum efficiency decreases rapidly. When the Ce charge amount (b) is 0.09 mol or more, it is considered that concentration quenching occurs. Therefore, from the perspective of the internal quantum efficiency, the Ce charge amount (b) is more preferably less than 0.09 mol.

[0065] Fig. 5 is a diagram showing the relationship between the Ce charge amount (b) and the absorption rate (Abs). Since Ce is an element that absorbs blue light and emits yellow light, the absorption rate increases with an increase in the Ce charge amount. For example, the absorption rate of the phosphor according to Example 6 (b = 0.09) is 86%, which is the maximum value among the examples. On the other hand, even if the Ce charge amount is further increased, the absorption rate remains constant at 86%. This is considered to be because the absorption of blue light by Ce has reached a saturation state. Also, when the Ce charge amount is decreased, the absorption rate of the phosphor according to Example 7 (b = 0.03) is 81%, and the characteristics within the target range (≧ 80%) are obtained.

[0066] However, the absorption rate of the phosphor according to Comparative Example 2 (b = 0.02) is 78%, and the characteristics within the target range are not obtained. This is considered to be because the Ce charge amount is insufficient. Therefore, when the phosphor according to Comparative Example 2 is combined with a blue LED to form a light-emitting module, it is considered that the required amount of phosphor increases and the directivity of the LED deteriorates. From the above, the Ce charge amount (b) considering the absorption rate is preferably more than 0.02 mol.

[0067] Next, the charge amount (a) of Ba is considered. As shown in Table 1, the emission intensity retention rate of the phosphor according to Example 8 (a = 0.03, b = 0.04) is 94%, and the characteristics within the target range are obtained. On the other hand, although the charge amount of Ce (b = 0.04) is the same as that of the phosphor of Example 8, the emission intensity retention rate of the phosphor of Comparative Example 3 (a = 0.01) where the charge amount of Ba (a) is less than that of the phosphor of Example 8 is 87%, and the characteristics within the target range are not obtained. This is presumably because when the charge amount of Ba (a) is as small as 0.01 mol, the effect of improving the emission intensity retention rate due to the solid solution of Ba is not significant. From the above, the charge amount (a) of Ba considering the emission intensity retention rate is preferably such that it satisfies the following L3. Equation L3: a > 0.01

[0068] FIG. 6 is a diagram showing the preferable ranges of the charge amount (a) of Ba and the charge amount (b) of Ce. As shown in FIG. 6, the phosphor according to the present embodiment has a general formula of Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b (However, a and b are values included in the range surrounded by the straight line represented by b = 0.1135a + 0.0754, the straight line represented by b = 0.0816a + 0.02, the straight line represented by a = 0.01, and the straight line represented by b = 0.12).

[0069] Thus, the yellow phosphor according to the present embodiment is a novel phosphor having good emission characteristics and temperature characteristics. Further, this yellow phosphor preferably emits light such that the chromaticity coordinates (cx, cy) satisfy 0.414 ≤ cx ≤ 0.453 and 0.532 ≤ cy ≤ 0.558. Thereby, for example, a white light source for a desired application can be realized in combination with a light emitting element that emits blue light having a peak wavelength in the range of 430 to 480 nm.

[0070] [Light Emitting Module] FIG. 7 is a schematic diagram of a light-emitting module according to the present embodiment. The light-emitting module 10 according to the present embodiment includes a mounting substrate 12, an LED 14 which is a light-emitting element mounted on the mounting substrate 12, and a light wavelength conversion layer 16 in which a phosphor is dispersed in a resin. The LED 14 emits blue light having a peak wavelength in the range of 430 to 480 nm. In the light wavelength conversion layer 16, a yellow phosphor according to the present embodiment is dispersed in a silicone resin transparent to visible light. Further, the light wavelength conversion layer 16 contains the yellow phosphor in an amount of 0.1 to 30 vol%, and has a thickness t of 0.01 to 5 mm. Note that the thickness may be in the range of 0.1 to 2 mm. The volume concentration of the yellow phosphor may be 10 vol% or less. Also, the volume average particle diameter (MV: Mean Volume Diameter) of the yellow phosphor may be 1 to 30 μm.

[0071] This light-emitting module 10 includes the light wavelength conversion layer 16 that is excited by the blue light emitted by the LED 14 and emits yellow light. The light wavelength conversion layer 16 contains the phosphor described above. In this light-emitting module 10, the emission color obtained by mixing blue light and yellow light has chromaticity coordinates (cx, cy) in the range surrounded by (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309). Thereby, it is possible to realize the light-emitting module 10 in which the emission color is in a range of chromaticity suitable for the above-described headlamp while achieving a desired luminous efficiency.

[0072] Further, the light wavelength conversion layer 16 may be a ceramic plate having a thickness of 0.01 to 2.0 mm. This ceramic plate is transparent to visible light and can be obtained by pressure-molding the phosphor and then performing vacuum firing or pressure firing. And in the light-emitting module 10, the LED 14 and the light wavelength conversion layer 16 may be joined at normal temperature.

[0073] Hereinafter, the light-emitting characteristics were evaluated for white light-emitting modules combining the phosphors of Examples 1, 4, and 6, which provide yellow light of the desired dominant wavelength and have emission intensity maintenance rates, internal quantum efficiency, and absorptance within the target ranges, with a blue LED. Fig. 8 is a diagram for explaining the relationship between the chromaticity of the emitted light of the light-emitting modules according to Examples 19 to 21 and the thickness of the light wavelength conversion layer containing a yellow phosphor.

[0074] (Example 19) 5 g of the phosphor (λd=569.0 nm) according to Example 1, 0.5 wt% TEOS (tetraethoxysilane), and 50 g of φ1 mm alumina balls were placed in a 100 ml polypot and rotated for 24 hours, then removed to a fluororesin-coated aluminum tray and dried by heating. The dried product was loosened using a nylon 50 mesh pass, weighed out in 1 g portions, placed in a φ20 mm mold, molded at 10 MPa, and further molded at 98 MPa using CIP (Cold Isostatic Pressing).

[0075] The molded product is placed in a vacuum furnace at 1 x 10 -3 The sintered body was then heated at 196 MPa, 1750°C, and 24 hours using HIP (Hot Isostatic Pressing) at 196 MPa, 1650°C, and 2 hours to obtain a transparent sintered body (transparent ceramic plate) with a thickness of approximately 1 mm. The transparent sintered body was polished to an arbitrary thickness using mirror polishing, cut into pieces of 1 mm square, and bonded at room temperature onto a blue LED chip to produce a light-emitting module according to Example 19 that realizes white light.

[0076] In the light-emitting module according to Example 19, when the thickness of the transparent sintered body, which is the light wavelength conversion layer, is 0.10 mm (the leftmost mark among the five chromaticity coordinates included in Example 19 in FIG. 8), 0.12 mm, 0.18 mm, 0.25 mm, or 0.30 mm (similarly the rightmost mark), the chromaticity of the light-emitting color (the light-emitting color obtained by mixing blue light and yellow light) of the light-emitting module falls within the desired chromaticity range R1 suitable for a headlamp. Note that, instead of a transparent ceramic plate, a transparent resin in which phosphor is dispersed may be used as the light wavelength conversion layer.

[0077] (Example 20) An emission module according to Example 20 was fabricated by the same manufacturing method as in Example 19, except that the phosphor according to Example 4 (λd = 567.4 nm) was used. For the emission module according to Example 20, when the thickness of the transparent sintered body was 0.10 mm (the left mark among the two chromaticity coordinates included in Example 20 of FIG. 8) and 0.15 mm (similarly the right mark), the chromaticity of the emission color of the emission module fell within the desired chromaticity range R1 suitable for a headlamp.

[0078] (Example 21) An emission module according to Example 21 was fabricated by the same manufacturing method as in Example 19, except that the phosphor according to Example 6 (λd = 570.5 nm) was used. For the emission module according to Example 21, when the thickness of the transparent sintered body was 0.15 mm (the leftmost mark among the three chromaticity coordinates included in Example 21 of FIG. 8), 0.20 mm, and 0.30 mm (similarly the rightmost mark), the chromaticity of the emission color of the emission module fell within the desired chromaticity range R1 suitable for a headlamp.

[0079] (Second Embodiment) [Background] In a phosphor in which Ba and Si are solid-solved in a YAG phosphor (hereinafter also referred to as a "BS-YAG phosphor"), cerium (Ce 3+ ) forms a structure factor (Ce site) of an oxygen (O) and a dodecahedron in the crystal. The Ce site shares an edge with a SiO4 tetrahedron (edge length 1.60 Å) or an AlO4 tetrahedron (edge length 1.74 Å) at two locations.

[0080] In the crystal of the BS-YAG phosphor, in the AlO4 tetrahedron formed by Al and O and the SiO4 tetrahedron formed by Si and O, the bond between Al and O (Al-O) and the bond between Si and O (Si-O) are equivalent. For this reason, the positions of Al and Si are fixed, and a strong tetrahedral unit is formed. Since this tetrahedral unit vibrates as a strong tetrahedron when the temperature rises, it is presumed that the Ce site sharing the edge receives a large lattice vibration, and as a result, a shift in the dominant wavelength occurs.

[0081] By substituting the Si (ionic radius 0.26 Å) in this SiO4 tetrahedron with phosphorus (P) (ionic radius 0.17 Å) which has a smaller ionic radius than Si, it is assumed that a PO4 tetrahedron (edge length 1.48 Å) smaller than the SiO4 tetrahedron is formed. In the PO4 tetrahedron formed by P and O, one of the bonds (P-O) with the four O atoms coordinated to P forms a double bond. For this reason, the position of P is not equivalent to the four O atoms, and P can vibrate (change its position) in the PO4 tetrahedron. As a result, the inventors conceived the possibility of realizing a phosphor that can suppress the influence of the thermal vibration of the Ce sites sharing the edges and suppress the shift of the dominant wavelength.

[0082] [Phosphor] In the second embodiment, mainly, the general formula is M a Y 3-a-b Al 5-a+c Si a-2c P c O 12 :Ce b (However, M represents at least one element selected from the group consisting of Ba, Sr, Ca, and Mg. a and b are values included in the range surrounded by the straight line represented by b = 0.1135a + 0.0754, the straight line represented by b = 0.0816a + 0.02, the straight line represented by a = 0.01, and the straight line represented by b = 0.12. c is a value where 0 ≦ c < a / 2.) The phosphor represented by will be described. Note that a > 0 and b > 0.

[0083] In addition, in the above general formula according to the present embodiment, when the amount of Si is not 0, a and c satisfy the relational expression a - 2c > 0 (that is, a / 2 > c). As the amount of P increases (that is, the value of c increases), the amount of Si decreases according to the increased amount. Thereby, charge balance in the phosphor is achieved. In the present embodiment, the value of a is 0.01 < a < 1.20. This makes it easier to achieve charge balance in the phosphor. Also, the value of c is preferably 0.01 ≤ c ≤ 0.16. Further, when the molar ratio of Si to P is expressed as (a - 2c) / c = a / c - 2, this molar ratio is preferably 0 < a / c - 2 < 8.0. Thereby, the shift amount of the dominant wavelength of the phosphor can be reduced. Also, the value of b according to the present embodiment is 0.02 < b < 0.12.

[0084] The phosphor according to the present embodiment is a phosphor that is excited by blue light and emits light. The phosphor may be, for example, a phosphor that is strongly excited by blue light having a peak wavelength in the range of 430 to 480 nm at 25°C and emits yellow light having a dominant wavelength in the range of 567 to 572 nm. Also, the crystal structure of the phosphor according to the present embodiment may be a garnet type with a space group of Ia3d. Further, the volume average particle diameter of this powdered phosphor according to the present embodiment may be, for example, 1 to 30 μm.

[0085] Hereinafter, the phosphor according to the present embodiment will be described with reference to examples. In the following examples, for the produced phosphor, the dominant wavelength at 200°C in addition to the dominant wavelength at 25°C was measured. The phosphor was evaluated by comparing the shift amount of the dominant wavelength (hereinafter also simply referred to as "shift amount"), which is the value obtained by subtracting the dominant wavelength at 25°C from the dominant wavelength at 200°C, with the target value.

[0086] Referring to FIG. 9, the target value of the shift amount will be described. FIG. 9 is a chromaticity diagram (CIE1931) showing the chromaticity of the emission colors of the phosphor and the blue LED. The range R1 shown in FIG. 9 is the chromaticity range defined as white light for a specific application (automotive headlight), and this range is the same as the range R1 described with reference to FIG. 1. The point C3 shown in FIG. 9 is the chromaticity coordinates of an example of a blue LED having a peak wavelength in the range of 430 to 480 nm.

[0087] Here, assume that the dominant wavelength of the phosphor at 25°C is 569.0 nm, and the chromaticity coordinates of the phosphor are at point C4. Also, assume that the dominant wavelength of the phosphor at 200°C is 570.5 nm, and the chromaticity coordinates of the phosphor are at point C5. At this time, the straight line connecting point C3 and point C4 passes through the center of the range R1. Also, the straight line connecting point C3 and point C5 passes through the lower limit of the range R1. Therefore, the target value of the shift amount is set to 1.5 nm (=570.5 nm - 569.0 nm), and the target is that the shift amount of the phosphor is below this target value.

[0088] In the following examples, similar to the examples according to the first embodiment, for the luminous intensity maintenance rate, the target value was 90%, for the internal quantum efficiency, the target value was 90%, and for the absorption rate, the target value was 80%. The phosphors prepared for each item were evaluated.

[0089] (Example 22) The phosphor according to Example 22 is a phosphor represented by Ba 0.05 Y 2.89 Al 4.95 Si 0.05 :Ce 3+ 0.06 In Example 22, the phosphor was prepared under the same conditions as in Example 1, and the emission characteristics and temperature characteristics were evaluated.

[0090] In the phosphor of Example 22, the targets were achieved for the items of luminous intensity maintenance rate, internal quantum efficiency, and absorption rate. However, in the phosphor of Example 22, the dominant wavelength at 25°C was 569.0 nm, and the dominant wavelength at 200°C was 570.5 nm. Therefore, in Example 22, the shift amount was 1.5 nm, and the target regarding the shift amount was not achieved.

[0091] The measurement results such as the production conditions and luminescence characteristics of the phosphors in the examples are summarized in Table 2.

[0092]

Table 2

[0093] (Example 23) The phosphor according to Example 23 is a phosphor containing P. Specifically, the phosphor according to Example 23 is a phosphor represented by a Y 3-a-b Al 5-a+c Si a-2c P c O 12 :Ce b and satisfies a = 0.05, b = 0.06, c = 0.01, that is, a phosphor represented by 0.05 Y 2.89 Al 4.96 Si 0.03 P 0.01 O 12 :Ce 0.06 .

[0094] In Example 23, in addition to the raw materials (BaCO3, Y2O3, CeO2, α - Al2O3, SiO2) used in Example 1, AlPO4 (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used as a raw material, and a phosphor was produced under the same conditions as in Example 22 except that the mol ratio was measured to be Ba = 0.05, Y = 2.89, Al = 4.960, Si = 0.03, P = 0.010, Ce = 0.06, and the luminescence characteristics, temperature characteristics, and shift amount were evaluated.

[0095] In the phosphor of Example 23, the dominant wavelength at 25 °C was 569.0 nm, and the dominant wavelength at 200 °C was 570.0 nm. Therefore, in the phosphor according to Example 23, the shift amount was 1.0 nm, which was 0.5 nm less than that of the phosphor according to Example 22 to which P was not added. As a result, in Example 23, the shift amount was below the target value, and the target regarding the shift amount was achieved. In addition, regarding the items of luminous intensity maintenance rate, internal quantum efficiency, and absorption rate, the targets were also achieved in the phosphor of Example 23.

[0096] (Example 24) The phosphor according to Example 24 is a phosphor represented by Ba 0.05 Y 2.89 Al 4.965 Si 0.02 P 0.015 O 12 :Ce 0.06 A phosphor was produced under the same conditions as in Example 23 except that the respective raw material powders similar to those in Example 23 were weighed so as to have a molar ratio of Ba = 0.05, Y = 2.89, Al = 4.965, Si = 0.02, P = 0.015, and Ce = 0.06, and the luminescence characteristics, temperature characteristics, and shift amount were evaluated.

[0097] In the phosphor according to Example 24, the dominant wavelength at 25 °C was 569.0 nm, and the dominant wavelength at 200 °C was 569.5 nm. Therefore, in the phosphor according to Example 24, the shift amount of the dominant wavelength was 0.5 nm, which was further 0.5 nm less than that of the phosphor according to Example 23.

[0098] (Example 25) The phosphor according to Example 25 is a phosphor represented by Ba 0.05 Y 2.89 Al 4.97 Si 0.01 P 0.02 O 12 :Ce 0.06It is a phosphor represented by []. In addition, except that each raw material powder similar to that of Example 23 was weighed so as to have a molar ratio of Ba = 0.05, Y = 2.89, Al = 4.970, Si = 0.01, P = 0.020, Ce = 0.06, a phosphor was produced under the same conditions as in Example 23, and the luminescence characteristics and temperature characteristics were evaluated.

[0099] In the phosphor according to Example 25, the dominant wavelength at 25 °C was 569.0 nm, and the dominant wavelength at 200 °C was 570.0 nm. Therefore, in the phosphor according to Example 25, the shift amount was 1.0 nm, and the target was achieved.

[0100] (Example 26) The phosphor according to Example 26 is Ba 0.05 Y 2.89 Al 4.975 P 0.025 O 12 :Ce 0.06 It is a phosphor represented by []. In Example 26, a phosphor was produced under the same conditions as in Example 23 except that it was weighed so as to have a molar ratio of Ba = 0.05, Y = 2.89, Al = 4.975, Si = 0.00, P = 0.025, Ce = 0.06, and the luminescence characteristics and temperature characteristics were evaluated.

[0101] In the phosphor according to Example 26, the target was achieved for the items of luminescence intensity maintenance rate, internal quantum efficiency, and absorption rate. However, in the phosphor according to Example 26, the dominant wavelength at 25 °C was 569.0 nm, and the dominant wavelength at 200 °C was 570.5 nm. Therefore, in the phosphor according to Example 26, the shift amount was 1.5 nm, and the target was not achieved for the shift amount.

[0102] (Examples 27, 31, 36, 41) In Examples 27, 31, 36, and 41, phosphors were prepared under the same conditions as in Example 22, except that the respective raw material powders similar to those in Example 22 were weighed so as to have the molar ratios shown in Table 2, and the luminescence characteristics and temperature characteristics were evaluated. Therefore, in Examples 27, 31, 36, and 41, phosphors were prepared without using raw materials containing P. In any of Examples 27, 31, 36, and 41, the shift amount did not fall below 1.5 nm, and the target regarding the shift amount was not achieved. Note that for the phosphors according to these examples, the targets were achieved for the items of luminescence intensity retention rate, internal quantum efficiency, and absorption rate.

[0103] (Examples 28 to 30, 33 to 35, 38 to 40, 43 to 45) In Examples 28 to 30, 33 to 35, 38 to 40, and 43 to 45, phosphors were prepared under the same conditions as in Example 23, except that the respective raw material powders similar to those in Example 23 were weighed so as to have the molar ratios shown in Table 2. For any of the phosphors according to the examples, the shift amount was less than 1.5 nm, and the target regarding the shift amount was achieved. Note that for the phosphors according to these examples, the targets were also achieved for the items of luminescence intensity retention rate, internal quantum efficiency, and absorption rate.

[0104] (Examples 32, 37, 42) In Examples 32, 37, and 42, phosphors were prepared under the same conditions as in Example 23, except that the respective raw material powders similar to those in Example 23 were weighed so as to have the molar ratios shown in Table 2. In Examples 32, 37, and 42, the raw material powders were weighed such that the molar ratio of P to Si was smaller than that in the other examples, specifically, such that the molar ratio of Si to P was 8.00. For any of the phosphors according to the examples, the shift amount of the dominant wavelength was 1.5 nm, and the target regarding the shift amount was not achieved. Note that for the phosphors according to these examples, the targets were achieved for the items of luminescence intensity retention rate, internal quantum efficiency, and absorption rate.

[0105] The manufacturing method of the phosphors according to Examples 22 to 45 and the evaluation of the shift amount have been described above. Hereinafter, the evaluation results of Examples 22 to 45 will be described in more detail.

[0106] As shown in Table 2, in all examples, the targets were achieved for the items of emission intensity maintenance rate, internal quantum efficiency, and absorption rate. In addition, in Examples 22, 27, 31, 36, 41 where the phosphor does not contain P, and in Examples 32, 37, 42 where the molar ratio of P to Si is small, the targets were also achieved for these items.

[0107] Among the examples where the phosphor contains P, in the examples where 0.01 ≦ c ≦ 0.16 is satisfied for c, in addition to the items of emission intensity maintenance rate, internal quantum efficiency, and absorption rate, the evaluation of the shift amount was good.

[0108] Among the examples where the phosphor does not contain P, for the composition (Ba = 0.05, Ce = 0.06) of Example 22 where the dominant wavelength at 25°C is 569.0 nm and the internal quantum efficiency, absorption rate, and emission intensity maintenance rate are at their maximum values, the relationship between the amount of P and the shift amount of the dominant wavelength was examined.

[0109] FIG. 10 is a diagram showing the relationship between the amount of P and the shift amount of the dominant wavelength in the phosphors according to Examples 22 to 26. In Examples 22 to 26, Ba = 0.05 and Ce = 0.06 in all cases. As shown in FIG. 10, when P = 0.015 (Example 24), the shift amount was 0.4 nm, which was the minimum value among the shift amounts of Examples 22 to 26.

[0110] When the amount of P was increased from Example 24 to P = 0.02 (Example 25), the shift amount increased to 1.0 nm. When the amount of P was further increased to P = 0.025 and Si = 0.00 (i.e., Si / P = 0), the shift amount was 1.5 nm and the target was not achieved. From the above, from the viewpoint of reducing the shift amount, c (i.e., the amount of P) in the general formula of the phosphor described above is preferably less than 0.025, and more preferably less than 0.016.

[0111] Next, the change in the relationship between Si / P and the shift amount according to the difference in the amount of Ba was examined.

[0112] Figure 11 is a diagram showing the relationship between Si / P and the shift amount for each Ba amount. In Figure 11, it is a diagram plotting Si / P for examples of each Ba amount (Ba = 0.05, 0.08, 0.10, 0.20, 0.40).

[0113] As shown in Figure 11, regardless of the difference in Ba amount, in the range where Si / P is 0 to 1.33, the larger the Si / P, the smaller the shift amount. Also, in the range where Si / P is 0 to 8.0, the shift amount reached the minimum value when Si / P was 1.33. For example, in Example 24, the shift amount was 0.4, which was the minimum value. As Si / P increased from 1.33, the shift amount increased, and when Si / P was 8.0, the shift amount was 1.5 nm and the target was not achieved. From the above, from the viewpoint of reducing the shift amount, Si / P is preferably greater than 0 and preferably less than 8.0.

[0114] [Light-emitting module] Even when using the phosphor according to the second embodiment, the light-emitting module 10 can be realized with reference to Figure 7. The light-emitting module 10 according to the present embodiment includes a mounting substrate 12, an LED 14 which is a light-emitting element mounted on the mounting substrate 12, and a light wavelength conversion layer 16.

[0115] The light wavelength conversion layer 16 contains the above-mentioned phosphor and emits yellow light when excited by blue light with a wavelength of 430 to 480 nm emitted by the LED 14. Therefore, the light-emitting module 10 can emit a mixed-color light of the blue light emitted by the LED 14 and the yellow light emitted by the light wavelength conversion layer 16. The chromaticity of this emitted light may be within the range surrounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), (0.311, 0.309). Thereby, the light-emitting module 10 can emit light having a chromaticity within a range suitable for the above-mentioned headlamp while achieving a desired luminous efficiency.

[0116] The wavelength conversion layer 16 may be formed by dispersing the yellow phosphor according to the present embodiment in a silicone resin that is transparent to visible light. Further, the wavelength conversion layer 16 may contain, for example, 0.1 to 30 vol% of the above-described phosphor. Further, the thickness t of the wavelength conversion layer 16 may be, for example, about 0.01 to 5 mm. Note that the thickness may be in the range of 0.1 to 2 mm.

[0117] Alternatively, the wavelength conversion layer 16 may be a ceramic plate having a thickness of 0.01 to 5.0 mm. This ceramic plate may be transparent to visible light, which is obtained by pressure molding the phosphor and then performing vacuum firing or pressure firing. And the light emitting module 10 may have the LED 14 and the wavelength conversion layer 16 joined at room temperature.

[0118] (Example 46) In Example 46, a light emitting module was fabricated using the phosphor according to Example 24. The phosphor according to Example 46 is the phosphor that has the smallest shift amount, and the light emission intensity retention rate, internal quantum efficiency, and absorption rate achieve the target values among the above examples.

[0119] First, the phosphor according to Example 24 was placed in a mold of φ20 mm × 1.5 mm and molded to obtain a molded product. Next, the molded product was fired under the conditions of 1550 °C for 4 h, and further pressure fired under the conditions of 50 MPa and 1500 °C × 1 h to produce a sintered body (ceramic plate). Next, the sintered body was processed into a 1 mm square, and the thickness of the sintered body was adjusted to 0.3 mm by polishing the sintered body. By joining this sintered body to a blue LED chip at room temperature as the wavelength conversion layer, a light emitting module according to Example 46 that realizes white light was fabricated, and the emission color of the light emitting module was measured.

[0120] (Examples 47, 48) In Examples 47 and 48, light emitting modules were fabricated in the same manner as in Example 46, except that the thicknesses of the wavelength conversion layers were 0.1 and 0.05 mm, respectively, and the emission colors of the light emitting modules were measured.

[0121] FIG. 12 is a diagram showing the emission colors of the light-emitting modules according to Examples 46 to 48. The square marks shown in FIG. 12 are the chromaticity coordinates of the emission colors of the light-emitting modules according to Examples 46 to 48 at 25°C. Further, the triangular marks shown in FIG. 12 are the chromaticity coordinates of the emission colors of the light-emitting modules according to Examples 46 to 48 at 200°C.

[0122] As shown in FIG. 12, the chromaticity coordinates of the emission colors of the light-emitting modules according to Examples 46 to 48 at 25°C all fell within the desired chromaticity range R1 suitable for a headlamp. More specifically, these chromaticity coordinates changed as a result of passing through approximately the center of the range R1 and varying on a straight line connecting the chromaticity coordinates of the phosphor and the chromaticity coordinates of the blue LED.

[0123] Also, the chromaticity coordinates of the emission colors of the light-emitting modules according to Examples 46 to 48 at 200°C all fell within the desired chromaticity range R1 suitable for a headlamp. More specifically, these chromaticity coordinates changed as a result of passing through the inside of the range R1 rather than the lower limit of the range R1 and varying on a straight line connecting the chromaticity coordinates of the phosphor and the chromaticity coordinates of the blue LED.

[0124] From the above Examples 46 to 48, it can be said that by adding P to BS-YAG, a white LED was realized that increased the emission intensity maintenance rate when the temperature was raised from 25°C to 200°C while reducing the shift amount of the dominant wavelength.

[0125] [Method for manufacturing phosphor using liquid phase method] In the above embodiment, mainly, a method for manufacturing a phosphor by a solid phase method using raw material powder was described. The method for manufacturing a phosphor is not limited to the solid phase method, and for example, a phosphor may be manufactured by a liquid phase method. For example, a phosphor may be manufactured by a liquid phase method such as a citric acid sol-gel method, a hexamine method, and a uric acid method.

[0126] (Example 49) In Example 49, a phosphor having the same composition as the phosphor according to Example 24 was produced using the citric acid sol-gel method.

[0127] First, yttrium nitrate hexahydrate was adjusted to a 1 mol / l aqueous solution of yttrium nitrate, barium acetate was adjusted to a 1 mol / l aqueous solution, cerium nitrate hexahydrate was adjusted to a 1 mol / l aqueous solution of cerium nitrate, and water-soluble silica was adjusted to a 1 mol / l aqueous solution. Also, trimethyl phosphate was adjusted to a 0.5 mol / l aqueous solution, and citric acid was adjusted to a 2 mol / l aqueous solution.

[0128] Into a 100 ml beaker, 4.502 g of aluminum nonahydrate was placed, and thereto were added 6.98 ml of the adjusted aqueous solution of yttrium nitrate, 0.12 ml of the adjusted aqueous solution of barium acetate, 0.05 ml of the adjusted aqueous solution of water-soluble silica, 0.07 ml of the adjusted aqueous solution of trimethyl phosphate, and 38.7 ml of the adjusted aqueous solution of citric acid to obtain a mixed aqueous solution.

[0129] The obtained mixed aqueous solution was heated to 80°C and stirred at a stirring speed of 400 rpm for 1 hr. Then, while maintaining the state where the mixed aqueous solution was being stirred, 5.7 ml of propylene glycol was added to the mixed aqueous solution, and the mixed aqueous solution was heated to 130°C. After the mixed aqueous solution was heated to 130°C, stirring was stopped and the state was maintained for 6 hours to synthesize a gel-like substance (citric acid ester).

[0130] With the gel-like substance placed in the beaker, the beaker was placed in an electric furnace and the gel-like substance was heated at 500°C for 2 hr. Thereby, the gel-like substance was decomposed to synthesize an ashed substance (hereinafter also referred to as "ash"). This ash was placed in an alumina crucible and heated in the air at 800°C for 12 hr to decarburize the ash, thereby synthesizing approximately 1.5 g of a phosphor raw material powder.

[0131] [Supplementary Note] As described above, the present invention has been described with reference to the above-described embodiments and each example. However, the present invention is not limited to the above-described embodiments and each example, and the present invention also includes those obtained by appropriately combining or substituting the configurations of the embodiments and each example. Further, based on the knowledge of those skilled in the art, it is possible to appropriately rearrange the combinations and processing orders in the embodiments and each example, and to add various design changes and other modifications to the embodiments and each example. Embodiments to which such modifications are added may also be included in the scope of the present invention.

[0132] In the above-described first and second embodiments, mainly, the example in which M included in the general formula M a Y 3-a-b Al 5-a+c Si a-2c P c O 12 :Ce b is Ba has been described. However, M is not limited to this, and M may be Sr, Ca, or Mg, which are other alkaline earth metals, or may be a combination of two or more elements selected from the group consisting of Ba, Sr, Ca, and Mg.

Explanation of Reference Numerals

[0133] 10 Light-emitting module, 12 Mounting substrate, 14 LED, 16 Light wavelength conversion layer.

Claims

1. The general formula is M ａ Y ３－ａ－ｂ Al ５－ａ＋ｃ Si ａ－２ｃ P ｃ O １２ : Ce ｂ (where M represents at least one element selected from the group consisting of Ba, Sr, Ca, and Mg. a and b are values included in the range surrounded by the straight line represented by b = 0.1135a + 0.0754, the straight line represented by b = 0.0816a + 0.02, the straight line represented by a = 0.01, and the straight line represented by b = 0.

12. c is a value where 0 ≦ c < a / 2.) and is represented by A phosphor, wherein a and c satisfy the formulas a / c - 2 < 8.0 and 0.01 ≤ c ≤ 0.

16.

2. The phosphor according to Claim 1, wherein the crystal structure is of the garnet type.

3. The phosphor according to Claim 1 or 2, which is excited by blue light having a peak wavelength in the range of 430 to 480 nm and emits yellow light having a dominant wavelength in the range of 567 to 572 nm.

4. The phosphor according to any one of Claims 1 to 3, wherein the volume average particle diameter is 1 to 30 μm.

5. An LED that emits blue light having a peak wavelength in the range of 430 to 480 nm, and a wavelength conversion layer that is excited by the blue light emitted by the LED and emits yellow light, wherein the wavelength conversion layer contains the phosphor according to any one of Claims 1 to 4, and a light emission color obtained by mixing the blue light and the yellow light has a chromaticity within a range surrounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), (0.311, 0.309). A light emitting module characterized by this.

6. The light emitting module according to Claim 5, wherein the wavelength conversion layer contains 0.1 to 30 vol% of the phosphor in a resin transparent to visible light and has a thickness of 0.01 to 5 mm.

7. The light emitting module according to Claim 5, wherein the wavelength conversion layer is a ceramic plate having a thickness of 0.01 to 2.0 mm.

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